It’s a busy beat. Though commercial traffic is just rebounding after a dip following the 2008 economic downturn, freight traffic has surged since the implementation of NAFTA and increased international trade.

That means more trucks on the road, especially in border states like Michigan. $52 billion worth of goods crossed the U.S.-Canada border in June 2015 alone.

The vast majority of that freight — in Michigan, about two-thirds of it — is carried by truck.

Policing trucks in one of the nation’s truck hotspots

The state’s busiest weigh station is on I-75 just south of Monroe. Just how busy is it?

“This section of I-75 between Toledo and Detroit is the second-busiest section of roadway for commercial traffic in the United States,” said Michigan State Police Lieutenant Steve Pascoe, 1st district commanding officer with the MSP’s commercial vehicle enforcement division. “We see up to 700 trucks an hour come over our scales here.”

I met Pascoe at the Monroe weigh station on the northbound side of the freeway. Coincidentally, the station on the southbound side was closed that day.

When I asked why, Pascoe said it’s because an officer was out with an injury. Stuff like that happens. Plus, he only has so many officers to work with.

“When I started in 1998, we had 21 motor carrier officers stationed at Monroe,” Pascoe said. “Right now we have 12.”

As we’re talking, motor carrier officer Nathan Daugherty is watching a constant stream of trucks rumble past at 30 miles an hour. He’s also got several computer panels flashing at him.

“As they’re going over right here, there’s two metal plates in the ground," said Daugherty. "That’s like a weigh-in motion scale. And what that does is it shows up on the computer screen there, approximately how much they weigh.”

Other sensors pick up more information: like how fast the truck is going, and how many axles it has. Daugherty says all that gives him a good sense of whether a truck is in compliance.

But he also has to do a quick visual check for a whole lot of other stuff, from license plates to windshield obstructions. Daugherty admits it’s a lot to process all at once.

“You need a routine, but at the same time, you can’t be stuck in that routine to check each truck,” he said.

Daugherty gets a hand from technology. The computer flags some potentially overweight trucks, and flashes a signal ordering them around back. There’s another set of scales back there for a stationary weigh-in — and if necessary, a complete inspection.

Motor carrier officer Nathan Daugherty on the job.

Credit Sarah Cwiek / Michigan Radio

But motor carrier officers can weigh trucks while on road patrol too. They're equipped with portable scales, and the same kind of "weigh-in-motion" sensors used at the weigh stations.

Lt. Pascoe says even if a weigh station is closed, that doesn’t mean no one is watching.

“We can do everything out of our cars that we can do here at this weigh station,” Pascoe said.

“That money … does not go to our roads”

All told, carrier officers issued more than 38,000 citations in 2014, although just over 10% of those were for overweight violations.

That generated about $4.5 million in fines. But here’s the thing about that money…

“That money collected goes to the libraries,” said State Rep. Marilyn Lane, a Macomb County Democrat. “It does not go to our roads.”

Lane, vice chair of the House Transportation Committee, thinks that law needs to change. She thinks another one should too: the World War Two-era state law that allows trucks up to 164,000 pounds on Michigan roads.

That’s the highest weight limit in the nation, and more than twice the federal standard.

On top of that, Michigan allows so-called “super loads” exceeding that amount — for a flat additional $50 a year.

Lane thinks all that needs to change. “We need to immediately, if nothing else, reduce our weights to 80,000 (pounds), and start preserving and protecting our pavement immediately,” she said.

But it turns out this issue of how much heavy trucks damage Michigan roads — and even how to measure that — is an issue of much debate.

Given the technical and political controversy, trucks and truck weights aren’t likely to be part of the roads funding conversation for at least the next two years.

But things might get a little better out on the highways.

The Michigan State Police commercial enforcement division hopes to start training 15-20 new motor carrier officers this fall. That means you could start seeing a few more stations displaying an “open” sign soon.

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